An investigation into the efficacy of hatchery disinfectants against strains of Staphylococcus aureus associated with the poultry industry.

The efficacy of 18 commercial disinfectants was investigated using the type strain, isolate 24 (I. 24), of pulsed-field gel electrophoresis pattern related Staphylococcus aureus that have shown to be associated with clinical disease in Northern Ireland broilers. Eight quartenary ammonium compound (QAC), four peroxygen, three amphoteric (AMP), one phenolic along with two chlorine-based disinfectants were tested at their manufacturer's recommended concentration (MRC) and at three 10-fold dilutions of the MRC. The efficacy of disinfectants against I. 24 was assessed in conditions with no hatchery organic matter (HOM) and in conditions with no HOM present. In addition, 17 S. aureus strains, related and non-related to I. 24 and obtained from the poultry industry were screened for any increase in resistance relative to I. 24. All disinfectants were effective against all test strains when tested in the absence of HOM. Products from the QAC and peroxygen groups were the most potent. The performance of all disinfectants was reduced in the presence of HOM. Under these conditions all chlorine-based, two out of three AMP, and one out of eight QAC disinfectants were not effective against I. 24 when tested at the MRC. The results emphasise the importance of proper application on appropriate areas, using the correct concentration and exposure time for the disinfectant.     

Brook trout occupancy in rivers and streams of the Mixedwood Plains Ecozone,Ontario

Brook trout (Salvelinus fontinalis) are an iconic freshwater salmonid native to northeastern North America. They prefer cold, clean rivers and lakes, and have been culturally, socially and economically valued for decades. Overharvest and deforestation associated with European settlement in southern Ontario, Canada led to notable declines in brook trout abundance in rivers and streams by the late 1800s. Today, they are threatened by further habitat degradation, non-native species, and climate change. In this study, we document brook trout occupancy in rivers and streams of the Mixedwood Plains Ecozone in southern Ontario, between 1970–1980 and 2000–2010. We used generalised linear models to determine occupancy variation between the two time periods at five spatial scales spanning multiple watershed levels. We detected a decline in occupancy between time periods for the tertiary (from 23% to 17%) and quaternary (from 35% to 22%) watershed scales. In the Credit River-Sixteen Mile Creek watershed, mean occupancy decreased to a third of past estimate (from 31% to 10%). For a subset of 86 sites with overlapping sampling in both periods no temporal trend was detected, but a post-hoc analysis indicated low statistical power (0.07), which suggested that more intensive sampling would be needed to better quantify brook trout occupancy changes at this scale. The occupancies quantified for the past period in our study may serve as benchmarks for brook trout restoration efforts.